Monolithic Power Systems Inc. MP38870DL-LF-P

Overview

MP38870DL-LF-P from Monolithic Power Systems is a monolithic synchronous step-down DC/DC converter with integrated 80mΩ high-side MOSFET and external low-side gate driver, delivering 3A continuous output current across 4.5V–14V input range, fixed 600kHz switching frequency, and adjustable 0.8V–(VIN−3V) output voltage - deployed in flat-panel TV power rails and digital set-top box point-of-load regulation.

For engineers reviewing the MP38870DL-LF-P datasheet, MP38870DL-LF-P pinout, MP38870DL-LF-P application, or MP38870DL-LF-P equivalent, key selection criteria include its 3mm×4mm QFN14 package thermal resistance (θJA = 48°C/W), cycle-by-cycle overcurrent protection threshold (4A), power-good indicator accuracy (±50mV hysteresis), and external synchronization capability (250kHz–1.5MHz).

Technical Context

The MP38870 operates in fixed-frequency peak-current-mode control with internal 0.8V reference and error amplifier driving COMP node for loop stability. Its PWM comparator compares sensed switch current against COMP-derived threshold, initiating turn-off when limit is reached within each cycle.

It integrates a 5V internal regulator powering gate drivers and analog blocks, with bootstrap circuitry (BST pin) enabling floating high-side drive for external synchronous MOSFET. UVLO (4.1V rising, 3.2V falling) and thermal shutdown (150°C trip, 140°C recovery) provide fault resilience without external supervision.

Key Specifications

Pinout & Package

MP38870DL-LF-P uses a thermally enhanced 3mm × 4mm, 14-pin QFN package with exposed thermal pad (connected to GND). The package supports ≤48°C/W junction-to-ambient thermal resistance on 1"² 1oz copper PCB.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with MP2315DJ-LF-Z and LM5116MH/NOPB, MP38870DL-LF-P uniquely balances integration (built-in 80mΩ FET + gate driver) and scalability (external sync FET support), making it optimal for 3A–4A distributed power systems where efficiency, footprint, and fault robustness are jointly critical.

Availability

MP38870DL-LF-P is available at Aetrix Electronics and suitable for flat-panel television power rails, digital set-top box SoC core supplies, and broadband gateway line cards requiring stable component supply, RoHS-compliant packaging, and long-term industrial temperature support (–40°C to +85°C).

Supply support for MP38870DL-LF-P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, headquartered in Kirkland, WA, with global design and support operations.

The MP38870 belongs to MPS's integrated synchronous buck converter product line, engineered for space-constrained, high-efficiency point-of-load regulation in consumer and communications equipment where thermal performance and EMI control are critical.

FAQ

What is the maximum allowable input voltage for MP38870DL-LF-P?

The absolute maximum input voltage is 16V, but recommended operating range is 4.5V to 14V. Exceeding 14V risks violating the 17V maximum V_SW rating during switching transitions and may trigger overvoltage stress on internal gate drivers and bootstrap circuitry.

Can MP38870DL-LF-P operate without an external synchronous MOSFET?

No - the MP38870DL-LF-P requires an external low-side MOSFET connected to the BG pin. It contains only a high-side switch; the BG driver is designed exclusively to control an external N-channel MOSFET for synchronous rectification.

How does the EN/SYNC pin function in shutdown mode?

Pulling EN/SYNC below 0.4V for ≥5µs forces full shutdown: internal regulator disables, COMP node discharges, and all switching ceases. During shutdown, quiescent current drops to ≤10µA, and PG goes high-impedance (not actively driven).

What is the purpose of the N/C pin (Pin 7)?

Pin 7 is internally unconnected and must remain electrically floating. It may be tied to GND in PCB layout only for mechanical reinforcement or thermal relief - no electrical function is assigned, and connection does not affect operation or reliability.

Is an external bootstrap diode required for reliable operation?

An external bootstrap diode (e.g., IN4148) is optional but recommended when V_OUT = 3.3V or 5V and duty cycle exceeds 65%, as it improves BST capacitor recharge efficiency and prevents gate drive dropout during high-duty-cycle operation.

How does the power-good (PG) pin behave during thermal shutdown?

During thermal shutdown, the PG pin remains asserted (high-impedance/open-drain) only if V_OUT stays within ±10% of regulation. If thermal shutdown causes output collapse, PG pulls low. Once shutdown ends and output recovers, PG returns high after a 1ms debounce delay.

What is the minimum output voltage achievable with MP38870DL-LF-P?

The minimum regulated output voltage is 0.8V, set by the internal 0.808V feedback reference. This is achieved using a resistor divider where R2 is selected per the formula R2 = R1 × 0.8V / (V_OUT − 0.8V), with R1 ≈ 40.2kΩ for optimal loop response.